Hot melt adhesive composition

Abstract

This invention relates to a hot melt adhesive composition comprising a styrene triblock copolymer component, and to related articles comprising at least one inner or outer surface coated with the hot melt adhesive composition.

Description

Technical Field

[0001] This invention relates to a hot melt adhesive composition comprising a styrene triblock copolymer component, and to related articles comprising at least one inner or outer surface coated with the hot melt adhesive composition. Technical Background

[0002] Hot melt adhesives (HM adhesives) are substances that are solid at room temperature and are generally free of water and solvents. They are applied in a molten state after being heated to a temperature typically between 100°C and 250°C, and most commonly between 130°C and 180°C, and then cured during cooling to form a seal (or adhesive joint) that ensures the connection between two substrates to be assembled. Hot melt adhesives are typically supplied as compositions comprising a thermoplastic polymer and optionally a tackifying resin and a plasticizer.

[0003] Hot melt adhesives are widely used in a variety of applications, such as packaging, binding, and woodworking, because of their good stability and the fact that they do not require solvents. These adhesives can also be used in nonwoven applications. For example, disposable nonwoven absorbent products are widely used in infant, incontinent adult, and feminine hygiene applications.

[0004] Typical disposable nonwoven absorbent products include disposable diapers, training pants, adult incontinence pads and underwear, feminine hygiene pads or panty liners, and surgical masks. These items are designed to receive and contain bodily fluids and are typically worn close to or against the skin.

[0005] To manufacture disposable nonwoven absorbent articles, hot melt adhesive compositions are typically used to bond the various substrates of the articles together because they provide rapid bonding compared to other adhesives such as water-based or solvent-based adhesive compositions (which require a drying step with water or solvent).

[0006] The hot melt adhesive composition suitable for this purpose should have appropriate adhesive strength to bond the substrate involved. More specifically, such hot melt adhesives should exhibit good adhesion under a wide variety of conditions.

[0007] Document WO 2012 / 006132 A2 relates to a hot melt adhesive for absorbent articles comprising a thermally reversible block copolymer and an α-methylstyrene resin, wherein the thermally reversible block copolymer comprises a polymer of vinyl aromatic hydrocarbons and conjugated diene compounds.

[0008] Document WO 2019 / 069610 A1 relates to an adhesive composition comprising a thermoplastic polymer as a base polymer, the composition being free of α-methylstyrene-based resins.

[0009] Document JP 2008 / 297441 A relates to a hot melt adhesive comprising a hydrogenated thermoplastic block copolymer (which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound), a tackifying resin and a plasticizer, wherein the hydrogenated thermoplastic block copolymer has a 10wt% toluene viscosity of 100 to 2,600 mPa·s at 30°C.

[0010] Document JP 2016 / 065121A relates to hot melt adhesives comprising thermoplastic block copolymers (which are copolymers of vinyl-based aromatic hydrocarbons and conjugated diene compounds, having a styrene content of 35 to 45 wt% and a diblock content of 50 to 90 wt%) and star-shaped styrene block copolymers (which have a viscosity of 25 wt% toluene solution at 25°C of 250 mPa·s or less).

[0011] Therefore, there is a need for hot-melt adhesive compositions that provide good adhesion, particularly in products based on nonwoven materials, to receive and contain bodily fluids. More specifically, there is a need for hot-melt adhesive compositions that provide good adhesion at a wide range of temperatures and at a wide range of different coating weights. Thus, there is a need for hot-melt adhesive compositions that exhibit stable peel strength, depending on temperature and add-on variations, especially in products based on nonwoven materials. Invention Overview

[0013] A first object of the present invention is to provide a hot melt adhesive composition comprising:

[0014] -A first polymer component consisting of at least one hydrogenated linear styrene triblock copolymer;

[0015] - A second polymer component consisting of at least one hydrogenated linear styrene triblock copolymer having a diblock content of 10 to 90%, preferably 20 to 80%;

[0016] - at least one tackifying resin; and

[0017] - At least one plasticizer;

[0018] The composition comprises a first polymer component and a second polymer component in a weight ratio of 1:1 or higher, preferably 3:2 to 10:1, more preferably 2:1 to 8:1;

[0019] The composition comprises a plasticizer and a total polymer component in a weight ratio of 2.6:1 or higher.

[0020] In some embodiments, the hydrogenated linear styrene triblock copolymer of the first polymer component is selected from SEBS, SEPS, SEEPS, SBBS and blends thereof; preferably selected from SEBS, SBBS and blends thereof; more preferably the copolymer is SEBS.

[0021] In some embodiments, the hydrogenated linear styrene triblock copolymer of the second polymer component is selected from SEBS, SEPS, SEEPS, SBBS and blends thereof; preferably selected from SEBS, SBBS and blends thereof; more preferably the copolymer is SEBS.

[0022] In some embodiments, the polymer component has a viscosity of 100 mPa·s or less, equivalent to a 10% by weight toluene solution at 30°C.

[0023] In some embodiments, the first polymer component has a styrene content of 10 to 50%, preferably 20 to 40%.

[0024] In some embodiments, the second polymer component has a styrene content of 5 to 50%, preferably 10 to 40%.

[0025] In some embodiments, it includes at least one additional polymer component, said additional polymer component comprising an additional styrene block copolymer selected from SB, SI, SBS, SIS, SIBS.

[0026] In some embodiments, the composition includes a coefficient of variation of temperature-dependent peel strength of less than 0.4.

[0027] In some embodiments, the composition includes a coefficient of variation of peel strength of less than 0.4 depending on the amount added.

[0028] In some embodiments, the composition is obtained by mixing a first polymer component, a second polymer component, a tackifying resin, and a plasticizer.

[0029] A second object of the present invention is to provide the composition as described above as an adhesive for bonding two substrates together, or as a coating on the surface of a substrate.

[0030] A third object of the present invention is to provide an article comprising at least one inner or outer surface coated with the hot melt adhesive composition as described above.

[0031] In some implementations, the inner or outer surface is a nonwoven fabric.

[0032] In some implementations, the product is selected from disposable diapers, disposable training pants, feminine hygiene pads, absorbent pads, surgical masks, and surgical coats.

[0033] This invention makes it possible to address the aforementioned needs. In particular, the invention provides a hot-melt adhesive composition that provides good adhesion at a wide range of temperatures and with a wide range of different coating weights, especially in products based on nonwoven materials, for receiving and containing bodily fluids. This is made possible by the hot-melt adhesive composition of the invention. In particular, it has been surprisingly found that the hot-melt adhesive composition according to the invention makes it possible to provide articles that exhibit stable peel strength depending on temperature and / or dosage fluctuations, especially in products based on nonwoven materials.

[0034] Implementation Plan Description

[0035] The invention will now be described in more detail in the following description without limitation.

[0036] definition

[0037] "Hot melt" means that the adhesive composition needs to be heated at at least 120°C, preferably at least 140°C, to be applied to the substrate. Therefore, a hot melt adhesive composition is solid at 23°C.

[0038] "Substantially free of" means less than 1% by weight, preferably less than 0.1% by weight, more preferably less than 0.01% by weight, and even more preferably about 0% by weight of the compound or hot melt adhesive composition.

[0039] "Styrene triblock copolymer" means a copolymer comprising two styrene-terminated blocks and a medium-chain block formed from at least one type of monomer different from styrene monomer.

[0040] "Styrene diblock copolymer" means a copolymer comprising a styrene-terminated block and a block formed of at least one type of monomer different from styrene monomer.

[0041] "Diblock content" indicates the weight ratio of diblock copolymers in the polymer component.

[0042] "Styrene content" indicates the weight ratio of styrene units in the block copolymer.

[0043] “SBBS” stands for styrene-butadiene-butene-styrene triblock copolymer.

[0044] “SBS” stands for styrene-butadiene-styrene triblock copolymer.

[0045] “SEBS” stands for styrene-ethylene-butene-styrene triblock copolymer.

[0046] “SEPS” stands for styrene-ethylene-propylene-styrene triblock copolymer.

[0047] “SEEPS” stands for styrene-ethylene-ethylene-propylene-styrene triblock copolymer.

[0048] “SIBS” stands for styrene-isoprene-butadiene-styrene triblock copolymer.

[0049] “SIS” stands for styrene-isoprene-styrene triblock copolymer.

[0050] “SBC” indicates a copolymer containing at least one styrene block, including styrene triblock copolymers and styrene diblock copolymers.

[0051] “SB” indicates styrene-butadiene diblock copolymer.

[0052] “SI” indicates styrene-isoprene diblock copolymer.

[0053] “SEB” stands for styrene-ethylene-butene diblock copolymer.

[0054] “SEP” stands for styrene-ethylene-propylene diblock copolymer.

[0055] "Viscosity of 10% by weight toluene melt at 30°C" indicates the viscosity of a 10% by weight solution using toluene as a solvent at 30°C. This viscosity is measured using a Brinell viscometer.

[0056] Hot melt adhesive composition

[0057] In a first aspect, the present invention relates to a hot-melt adhesive composition comprising a first polymer component, a second polymer component, a tackifying resin, and a plasticizer. It may also contain other additional components.

[0058] First polymer component

[0059] The hot melt adhesive composition comprises a first polymer component.

[0060] The first polymer component consists of a hydrogenated linear styrene triblock copolymer. The first polymer component is substantially free of diblock copolymers.

[0061] The hydrogenated linear styrene triblock copolymer of the first polymer component may be selected from SEBS, SEPS, SEEPS, SBBS and blends thereof; preferably selected from SEBS, SBBS and blends thereof; more preferably the copolymer is SEBS.

[0062] In a preferred embodiment, the first polymer component consists of only one type of hydrogenated linear styrene triblock copolymer. In an alternative embodiment, the first polymer component is a blend of at least two hydrogenated linear styrene triblock copolymers.

[0063] The first polymer component may have a styrene weight content of 10 to 50%, preferably 20 to 40%, based on the total weight of the first polymer component.

[0064] The first polymer component may have a viscosity of 10 wt% toluene solution at 30°C of 100 mPa·s or lower, preferably 20 to 90 mPa·s (10 wt% TSV@30°C). This viscosity is measured using a Brinell viscometer.

[0065] For example, the first polymer component may be made by Kraton TM Product Names Supplied G-1650 and G-1652 or the trade name supplied by TSRC Corporation / Dexco Polymers SEBS 6153 obtained.

[0066] The hot melt adhesive composition may contain 5 to 20% by weight, preferably 6 to 17% by weight, more preferably 7 to 14% by weight, relative to the total weight of the composition.

[0067] Second polymer component

[0068] The hot melt adhesive composition contains a second polymer component.

[0069] The second polymer component comprises a hydrogenated linear styrene triblock copolymer having a diblock content of 10 to 90%, preferably 20 to 80%. In one embodiment, the hydrogenated linear styrene triblock copolymer of the second polymer component has a diblock content of 10 to 49%, preferably 20 to 40%. In an alternative embodiment, the hydrogenated linear styrene triblock copolymer of the second polymer component has a diblock content of 50 to 90%, preferably 60 to 80%.

[0070] The hydrogenated linear styrene triblock copolymer of the second polymer component can be selected from SEBS, SEPS, SEEPS, SBBS and their blends; preferably selected from SEBS, SBBS and their blends; more preferably the copolymer is SEBS.

[0071] In a preferred embodiment, the second polymer component consists of only one type of hydrogenated linear styrene triblock copolymer. In an alternative embodiment, the second polymer component is a blend of at least two hydrogenated linear styrene triblock copolymers.

[0072] The second polymer component may have a styrene weight content of 5 to 50%, preferably 10 to 40%, based on the total weight of the second polymer component.

[0073] The second polymer component may have a viscosity of 10 wt% toluene solution at 30°C of 100 mPa·s or lower, preferably 5 to 100 mPa·s (10 wt% TSV@30°C). This viscosity is measured using a Brinell viscometer.

[0074] For example, the second polymer component can be derived from Kraton. TM Product Names Supplied G-1657 G-1726 and G-1924 or the trade name supplied by LCY 9557 and 9526 was obtained.

[0075] The hot melt adhesive composition may contain 1 to 10% by weight, preferably 1 to 8% by weight, and more preferably 2 to 5% by weight relative to the total weight of the composition.

[0076] The weight ratio between the first polymer component and the second polymer component

[0077] The hot melt adhesive composition may include a first polymer component and a second polymer component in a weight ratio of 1:1 or higher, preferably 3:2 to 10:1, more preferably 2:1 to 8:1.

[0078] Additional polymer components

[0079] The hot melt adhesive composition may contain additional polymer components. In an alternative embodiment, the hot melt adhesive composition may be substantially free of any additional polymer components.

[0080] This additional polymer component may comprise an additional styrene block copolymer (SBC) that is different from the hydrogenated linear styrene triblock copolymer described above in the first and second polymer components. Such additional polymer components can be obtained from a wide variety of chemical and structural types. Examples of suitable additional styrene block copolymers are selected from SB, SI, SBS, SIS, and SIBS; SIS is preferred.

[0081] If present, the hot melt adhesive composition may contain 0.1 to 10% by weight, preferably 1 to 5% by weight, of an additional polymer component relative to the total weight of the composition.

[0082] Total polymer components

[0083] The hot melt adhesive composition may contain 6% to 30% by weight, more preferably 7% to 25% by weight, and more preferably 9% to 19% by weight of total polymer components relative to the total weight of the composition.

[0084] Tackifying resin

[0085] The hot melt adhesive composition contains a tackifying resin (tackifier). The hot melt adhesive composition may contain 35 to 75% by weight, preferably 45 to 70% by weight, and more preferably 50 to 60% by weight of the tackifying resin relative to the total weight of the composition.

[0086] Suitable tackifying resins are those that are compatible with the polymer components, enhance adhesive properties, and improve specific adhesion. As used herein, the term "tackifying resin" includes:

[0087] - Such as aliphatic and alicyclic petroleum hydrocarbon resins with a ring and ball softening point of 90°C to 160°C as determined by ASTM method E28-58T, the latter resins being produced by polymerization of monomers consisting primarily of aliphatic and / or alicyclic olefins and dienes; also including hydrogenated aliphatic and alicyclic petroleum hydrocarbon resins, examples of such commercially available resins based on the C5 olefin fraction are Piccotac 95 tackifying resin sold by Eastman Chemical and Escorez 1310LC sold by ExxonMobil Chemical Company;

[0088] -Aromatic petroleum hydrocarbon resins and their hydrogenated derivatives;

[0089] -Aliphatic / aromatic petroleum-derived hydrocarbon resins and their hydrogenated derivatives;

[0090] -Aromatic modified alicyclic resins and their hydrogenated derivatives;

[0091] - Polyterpene resins with softening points of 95°C to 140°C, the latter of which are typically produced by the polymerization of terpenes (e.g., monoterpenes called pinene) at medium to low temperatures in the presence of a Fred-Cleif catalyst; also including hydrogenated polyterpene resins.

[0092] - Copolymers and terpolymers of natural terpenes, such as styrene / terpenes, α-methylstyrene / terpenes, and vinyltoluene / terpenes;

[0093] - Natural and modified rosins, such as, for example, gun rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin and polymerized rosin;

[0094] - Glyceryl esters and pentaerythritol esters of natural rosin and modified rosin, such as, for example, glyceryl esters of light-colored rosin, glyceryl esters of hydrogenated rosin, glyceryl esters of polymerized rosin, pentaerythritol esters of light-colored rosin, pentaerythritol esters of hydrogenated rosin, pentaerythritol esters of tall oil rosin, and phenolic modified rosin pentaerythritol esters; and

[0095] - Phenolic modified terpene resins, such as resin products produced by the condensation of terpenes and phenols in an acidic medium.

[0096] In a preferred embodiment, the resin is not modified by unsaturated polycarboxylic acids, anhydrides, or esters (in other words, the composition does not contain any resin modified by unsaturated polycarboxylic acids, anhydrides, or esters).

[0097] A mixture of two or more of the above-mentioned tackifying resins may also be used.

[0098] The tackifying resins that can be used in this invention may include polar tackifying resins. However, given that many polar resins appear to be only partially compatible with polyolefin polymers, the selection of available polar tackifying resins is limited.

[0099] Alternatively, the tackifying resin can be selected from any commercially available nonpolar type. A preferred class of resins are aliphatic petroleum hydrocarbon resins, examples of which are based on C5 olefins. Most preferred are nonpolar products based on hydrogenated dicyclopentadiene (DCPD) or its aromatic modified derivatives, with a softening point above 95°C. Examples of such resins are Escorez 5340, Escorez 5400, and Escorez 5600 sold by ExxonMobil Chemical, Sukorez SU-120 sold by Kolon, and JH6130 sold by Jinhai.

[0100] Preferably, the tackifying resin should have a ring and ball softening point of at least 90°C, and more preferably 90°C to 140°C (measured by ASTM E28). Generally, the tackifying resin should be substantially aliphatic to ensure compatibility between the resin and polymer components.

[0101] plasticizer

[0102] The hot melt adhesive composition of the present invention includes a plasticizer. The plasticizer may be a solid or liquid plasticizer.

[0103] The hot melt adhesive composition may contain 5 to 45% by weight, preferably 10 to 40% by weight, and more preferably 25 to 35% by weight, relative to the total weight of the composition.

[0104] The purpose of plasticizers is to provide the desired viscosity control and impart flexibility. Suitable plasticizers can be selected from the group consisting of conventional plasticizing oils (e.g., mineral oils), as well as olefin oligomers and low molecular weight polymers, and vegetable and animal oils and derivatives of such oils. Petroleum-derived oils that can be used are relatively high-boiling materials containing only a small fraction of aromatic hydrocarbons. Oligomers can be polypropylene, polybutene, hydrogenated polyisoprene, hydrogenated polybutene, etc., having an average molecular weight between 350 and 10,000. Suitable vegetable and animal oils include glycerides of conventional fatty acids and their polymers. Any number of different plasticizers can be used in this invention, but mineral oils and liquid polybutene (having an average molecular weight of less than 5,000) are particularly advantageous.

[0105] Plasticizers are typically used to reduce the viscosity of the entire hot melt adhesive composition without substantially reducing the adhesive strength and / or service temperature of the adhesive composition, as well as to extend the open time and improve the flexibility of the composition.

[0106] The weight ratio between plasticizer and total polymer components

[0107] The compositions of the present invention exhibit a weight ratio of 2.6:1 or higher between the plasticizer and the total polymer components. This is an advantageous ratio because it makes it possible to provide articles with stable peel strength under a wide variety of conditions, such as temperature and dosage.

[0108] In one embodiment, the composition of the present invention presents a weight ratio between the plasticizer and the total polymer components of 2.6:1 to 10:1, preferably 2.6:1 to 5:1.

[0109] Other additives

[0110] The hot melt adhesive composition of the present invention preferably also includes at least one stabilizer (antioxidant).

[0111] The hot melt adhesive composition may contain 0.1 to 5% by weight, preferably 0.5 to 3% by weight, of a stabilizer relative to the total weight of the composition.

[0112] Incorporating suitable stabilizers helps protect the aforementioned polymers, and thereby protects the entire adhesive system from thermal and oxidative degradation that typically occurs during adhesive manufacturing and application, as well as when the final product is routinely exposed to the surrounding environment.

[0113] Suitable stabilizers include high molecular weight hindered phenols and polyfunctional phenols, such as sulfur- and phosphorus-containing phenols. Hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds containing spatially large groups immediately adjacent to their phenolic hydroxyl groups. In particular, the tert-butyl group is typically substituted into at least one ortho position relative to the phenolic hydroxyl group on the benzene ring. The presence of these spatially large substituents near the hydroxyl group helps to slow down its stretching frequency and correspondingly reduce its reactivity; this steric hindrance thus provides the phenolic compound with its stabilizing properties. Representative hindered phenols include: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4′-methylenebis(4-methyl-6-tert-butylphenol); 2,6-di-tert-butylphenol; 6-(4-hydroxybenzyl)propionate; 2,4-bis(n-octylthio)-1,3,5-triazine; 2,3,6-tris(4-hydroxy-3,5-di-tert-butyl-phenoxy)-1,3,5-triazine; di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate; 2-(n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxybenzoate and sorbitol hexa-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0114] Pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is particularly preferred as a stabilizer.

[0115] The performance of these stabilizers can be further enhanced by combining them with: (1) synergists, such as, for example, dithiodipropionate and phosphites; examples of these include dilauryl thiodipropionate (DLTDP) and tris(nonylphenyl) phosphite (TNPP); and (2) chelating agents and metal passivators, such as ethylenediaminetetraacetic acid, its salts and bis(salicylic acid)propanediamine.

[0116] The hot melt adhesive composition according to the invention may further include at least one wax. The hot melt adhesive composition may contain 0 to 30% by weight, preferably 0.5 to 3% by weight, of wax relative to the total weight of the composition.

[0117] The presence of wax makes it possible to reduce the melt viscosity of hot melt adhesives without significantly reducing their bonding properties. These waxes are also used to reduce the open time or preparation time of compositions without affecting temperature performance.

[0118] Useful wax materials include:

[0119] - Low molecular weight, i.e., number average molecular weight (Mn) of polyethylene wax from 100 to 6000 g / mol, having a hardness value of 0.1 to 120 and an ASTM softening point of 65°C to 140°C as determined by ASTM method D-1321.

[0120] - Petroleum waxes, such as paraffin wax with a melting point of 50°C to 80°C and microcrystalline wax with a melting point of 55°C to 100°C, the latter of which is determined by ASTM method D127-60.

[0121] - Metallocene-catalyzed propylene-based waxes, such as those commercialized by Clariant under the name "Licocene";

[0122] - Metallocene-catalyzed waxes or single-point-catalyzed waxes, such as those described in US 4,914,253, US 6,319,979, WO 97 / 33921 ​​or WO 98 / 03603;

[0123] - Synthetic waxes produced by the polymerization of carbon monoxide and hydrogen, such as Fischer-Tropsch wax; and

[0124] - Polyolefin waxes. As used herein, the term "polyolefin wax" refers to polymeric or long-chain entities composed of olefinic monomer units. These materials are commercially available from Westlake Chemical Co. under the trade name "Epolene".

[0125] Preferably, the wax material used has a ring and ball softening point of 93°C to 177°C. It should be understood that each of these waxes is solid at room temperature. Other useful substances include hydrogenated animal, fish, and vegetable fats and oils, such as hydrogenated tallow, lard, soybean oil, cottonseed oil, castor oil, menhadin oil, cod liver oil, etc., which are also found useful as wax material equivalents because they are hydrogenated and solid at ambient temperature. These hydrogenated materials are commonly referred to as “animal or vegetable waxes” in the adhesives industry. According to some embodiments, the compositions of the present invention may contain acid-modified components. Such compounds may include, for example, waxes, resins (e.g., petroleum or tackifying resins), softeners, oils, plasticizers, or rubbers, preferably resins. In other words, the compositions of the present invention may contain components (preferably resins) modified by unsaturated polycarboxylic acids, anhydrides, or esters (thereby containing one or more acidic groups). Examples of polycarboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, and polycarboxylic acids. An example of such compounds is Quintone D295, an acid-modified resin sold by Zeon. According to some embodiments, other optional auxiliary additives may be incorporated into the hot melt adhesive composition to modify one or more physical properties of the composition. The hot melt adhesive composition may contain 0.01 to 3% by weight of auxiliary additives relative to the weight of the composition.

[0126] Such additives may include, for example, inert colorants such as titanium dioxide, as well as fillers, surfactants, other types of polymers, crosslinking agents, nucleating agents, reactive compounds, flame-retardant inorganic or organic reagents, ultraviolet (UV) or infrared (IR) light absorbers, and UV or IR fluorescent agents. Typical fillers include talc, calcium carbonate, clay, silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, and wood flour. These optional auxiliary additives are well known in the art.

[0127] In a preferred embodiment, the composition of the present invention does not contain butyl rubber.

[0128] In a preferred embodiment, the composition of the present invention comprises:

[0129] -5 to 20% by weight, preferably 6 to 17% by weight, more preferably 7 to 14% by weight, relative to the total weight of the composition;

[0130] -As defined above, the second polymer;

[0131] - 35 to 75% by weight, preferably 45 to 70% by weight, more preferably 50 to 60% by weight, relative to the total weight of the composition;

[0132] - 5 to 45% by weight, preferably 10 to 40% by weight, more preferably 25 to 35% by weight, relative to the total weight of the composition;

[0133] The composition comprises a first polymer component and a second polymer component in a weight ratio of 3:2 to 10:1, more preferably 2:1 to 8:1; and

[0134] The composition comprises a plasticizer and a total polymer component in a weight ratio of 2.6:1 or higher, preferably 2.6:1 to 10:1, and even more preferably 2.6:1 to 5:1.

[0135] Viscosity

[0136] The hot-melt adhesive composition of the present invention has a viscosity of 1,000 to 40,000 mPa·s, preferably 5,000 to 35,000 mPa·s, at a temperature of 120°C. The viscosity can be measured in a Brinell RVT viscometer (rotor 27) according to ASTM D3236.

[0137] softening point

[0138] The hot melt adhesive composition of the present invention may have a softening point of 70 to 120°C, preferably 85 to 110°C. The softening point can be measured according to ASTM E-28 standard.

[0139] Peel strength

[0140] The hot-melt adhesive composition of the present invention makes it possible to obtain stable peel strength under a wide variety of conditions. More particularly, the hot-melt adhesive composition makes it possible to obtain articles having relatively stable peel strength relative to increasing temperature and increasing amount added. "Amount added" refers to the weight of the coating formed by the hot-melt adhesive composition. "Relatively stable" means that the coefficient of variation of peel strength depending on temperature is less than 0.4, and the coefficient of variation of peel strength depending on amount added is also less than 0.4.

[0141] Therefore, the coefficient of variation of temperature-dependent peel strength can be less than 0.4. For example, the coefficient of variation of temperature-dependent peel strength can be 0.1 to 0.15; or 0.15 to 0.2; or 0.2 to 0.25; or 0.25 to 0.3; or 0.3 to 0.35; or 0.35 to less than 0.4.

[0142] In addition, the coefficient of variation of peel strength depending on the amount added may also be less than 0.4. For example, the coefficient of variation of peel strength depending on the amount added may be 0.1 to 0.15; or 0.15 to 0.2; or 0.2 to 0.25; or 0.25 to 0.3; or 0.3 to 0.35; or 0.35 to less than 0.4.

[0143] The coefficients of variation for temperature dependence and addition amount dependence are measured as follows:

[0144] First, the hot melt adhesive composition is heated to 140 to 150°C, and then applied through a slot (open time of 0.3 seconds and compression (pressure) at the pinch roller of 0.01 MPa) at 20, 30, 40, and 50 g / m². 2 The coating weight is applied to the main substrate, which is the release paper. The hot melt adhesive composition has a pattern of 13 stripes (lines), each stripe being 2 mm wide. The spacing between the stripes is 2 mm. A second substrate (impermeable polyethylene (PE) film) is then laminated to the main substrate containing the composition. The composition is transferred to the impermeable PE film side to prepare a sample. The laminate is then stored at 23°C and 50% relative humidity for 24 hours to cool and cure the hot melt adhesive. The laminate is then cut to obtain a specimen with a width of 50 mm and a length of 100 mm in the transverse direction.

[0145] For measuring peel strength at 40°C: The sample and cotton cloth were stored at 40°C for 3 hours. After removing the release paper from the sample, the sample was applied to the cotton cloth and pressed back and forth with a 2kg roller. Following this, a T-peel test was performed at 40°C at a speed of 300mm / min using a Tensilon tester, and the initial peel strength was measured.

[0146] For measuring peel strength at 0, 23 and 30°C, the same procedure can be followed at 0, 23 and 30°C respectively.

[0147] For measuring the temperature-dependent coefficient of variation: for each coating weight (20, 30, 40, and 50 g / m²) 2 Calculate the average peel strength.

[0148] For each coating weight (20, 30, 40 and 50 g / m²) 2 The standard deviation was also calculated.

[0149] The coefficient of variation is calculated by dividing the standard deviation of each coating weight by the average peel strength of each and the corresponding coating weight.

[0150] For the coefficient of variation dependent on the amount of additive: the average peel strength was calculated for each temperature (0, 23, 30, and 40°C). The standard deviation was also calculated for each temperature (0, 23, 30, and 40°C).

[0151] The coefficient of variation is calculated by dividing the standard deviation of each temperature by the average peel strength at each and corresponding temperatures.

[0152] Hot melt adhesive composition (method-defined product)

[0153] This hot melt adhesive composition can be obtained by mixing the first polymer component, the second polymer component, the tackifying resin, the plasticizer, and any additional components as described above.

[0154] use

[0155] In a second aspect, the present invention relates to the use of the hot melt adhesive composition as described above for coating a substrate or for bonding two substrates together.

[0156] Each substrate to be coated or bonded may include a film, a nonwoven material, or a woven material. It may include absorbent fibers, superabsorbent polymers (SAP), composite materials, plastics that can be elastomers or non-elastomers, such as styrene block copolymers (SBCs), polyurethanes and polyolefins, and any mixtures thereof. Preferably, the substrate is a nonwoven fabric.

[0157] In this context, methods for manufacturing assembled products (or laminates) may include:

[0158] - Step (i): The hot melt adhesive composition according to the invention is heated, for example, at a temperature in the range of 120°C to 180°C for at least a sufficiently long time, so that the hot melt adhesive composition is sufficiently liquid to be applied to the substrate (e.g., at least two hours), and then

[0159] -Step (ii): Apply the composition to the first substrate, then

[0160] - Step (iii): Make the coated surface of the first substrate come into contact with the surface of the second substrate to form an adhesive joint that bonds the two substrates.

[0161] The substrate can be different or have the same properties, and can take various forms (layers or films, wires, fibers).

[0162] Products

[0163] In a third aspect, the present invention relates to articles comprising at least one inner or outer surface coated with a hot-melt adhesive composition as described above. In a particular embodiment, the present invention relates to an assembled product comprising at least two substrates bonded together by at least one hot-melt adhesive composition according to the invention.

[0164] The coating surface and the adhesive substrate can be as described above.

[0165] The hot-melt adhesive composition according to the invention can be used as a laminating adhesive to bond multiple base layers, for example, in the manufacture of toilet paper, tissues, wipes and other consumer products, particularly absorbent articles such as disposable hygiene products, and more particularly disposable diapers.

[0166] In some embodiments, the assembled product according to the invention may be a multilayer product comprising at least two base layers bonded together by at least one hot melt adhesive composition according to the invention.

[0167] In the assembled product according to the invention, at least two base layers can be bonded together by means of a layer of hot melt adhesive composition according to the invention sandwiched between the two base layers.

[0168] Alternatively or cumulatively, at least two substrate layers may be joined by point bonding using a hot melt adhesive composition according to the invention.

[0169] Preferably, the article / assembled product is a disposable nonwoven absorbent article. Examples include disposable diapers, disposable training pants, disposable adult incontinence pads or shorts, disposable feminine hygiene pads or panty liners, surgical masks, and surgical gowns. Example

[0170] The following examples illustrate the present invention but do not limit the scope of the invention.

[0171] To investigate the coefficients of variation of temperature-dependent and addition-dependent coefficients, eight compositions were prepared. Compositions A to D are according to the present invention, while compositions E to H are comparative compositions.

[0172] Compositions A to H include some of the following compounds:

[0173] -SEBS1: Supplied by TSRC Corporation / Dexco Polymers SEBS 6153 contains 29% styrene, 0% diblock, and has a viscosity of 55 mPa·s at 30°C for a 10% by weight toluene solution (corresponding to the first polymer component).

[0174] -SEBS2: Available from Kraton G-1726 contains 30% styrene, 70% diblock, and a viscosity of 10 mPa·s at 30°C for a 10% by weight toluene solution (corresponding to the second polymer component).

[0175] -SEBS3: Available from Kraton G-1657 contains 13% styrene, 29% diblock, and has a viscosity of 65 mPa·s for a 10% by weight toluene solution at 30°C (corresponding to the second polymer component).

[0176] -R1: Available from Kolon SU-12 is a fully hydrogenated DCPD resin.

[0177] -R2: Available from Jinhai JH6130, which constitutes hydrogenated DCPD resin.

[0178] -R3: Available from Zeon D295 is an acid-modified non-hydrogenated petroleum resin. This resin is modified with maleic acid and has a softening point of 94°C and an acid value of 8.0 mg KOH / g.

[0179] -P1: Apar available from Apar H350 is a paraffin oil plasticizer.

[0180] -A1: Antioxidant 1010 is a hindered phenolic antioxidant available from BASF.

[0181] SEBS1 (%) 9.5 9.5 9.5 9.5 13 13 11.5 10 SEBS2 (%) - - - - 3 3 - SEBS3 (%) 3 3 3 3 - - - 3 R1(％) - - 54.5 - 57.2 57.2 - 57 R2(％) 54.5 51.5 - 52.5 - - 52.5 R3(％) - 3 - - - - - - P1(％) 32.5 32.5 32.5 34.5 29.5 26.5 32.5 29.5 A1(％) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Plasticizer / Polymer 2.6 2.6 2.6 2.76 2.27 1.66 2.24 2.27

[0182] Compositions A to H are prepared by the following steps: The components listed in the table above are placed in a jacketed mixing vessel equipped with a heater and a stirrer, and then mixed while being heated at 170°C under vacuum for 120 minutes to remove any trapped air.

[0183] The viscosity of compositions A through H was measured in a Brinell RVT viscometer according to ASTM D3236 standard.

[0184] The softening points of compositions A through H were measured according to ASTM E-28 standard.

[0185] The results are presented in the table below:

[0186] A 18060 96.6 B 15810 96.3 C 10150 91.7 D 15500 95.9 E 17690 96.8 F 32000 97.8 G 26380 100.3 H 13750 93.8

[0187] As detailed in the description above, the coefficients of variation (CV) for temperature dependence and addition amount dependence were measured.

[0188] <![CDATA[20g / m 2 Temperature dependence CV 0.29 0.33 0.25 0.34 0.39 0.65 0.35 0.43 <![CDATA[30g / m 2 Temperature dependence CV 0.36 0.33 0.30 0.36 0.41 0.52 0.34 0.38 <![CDATA[40g / m 2 Temperature dependence CV 0.34 0.32 0.25 0.30 0.44 0.55 0.27 0.41 <![CDATA[50g / m 2 Temperature dependence CV 0.38 0.36 0.23 0.34 0.47 0.56 0.31 0.43 CV of addition amount at 0℃ 0.22 0.17 0.22 0.22 0.15 0.29 0.28 0.26 CV of addition amount at 23℃ 0.28 0.20 0.26 0.23 0.29 0.19 0.32 0.28 CV of addition amount at 30℃ 0.37 0.25 0.31 0.25 0.27 0.25 0.38 0.28 CV of addition amount at 40℃ 0.32 0.24 0.29 0.28 0.34 0.24 0.45 0.28

[0189] As can be seen from the table above, in contrast to the comparative compositions (E to H), the compositions (A to D) according to the invention make it possible to simultaneously achieve good temperature-dependent CV (CV less than 0.4) at all coating weights and good addition-dependent CV (CV less than 0.4) at all temperatures.

Claims

1. A hot melt adhesive composition, comprising, relative to the total weight of the composition: -5 to 20% by weight of a first polymer component consisting of at least one hydrogenated linear styrene triblock copolymer, which is substantially free of diblock content; - A second polymer component consisting of at least one hydrogenated linear styrene triblock copolymer having a diblock content of 10 to 90%; -35 to 75% by weight of at least one tackifying resin; and - At least one plasticizer; The composition comprises a first polymer component and a second polymer component in a weight ratio of 1:1 or higher; and The composition wherein the weight ratio between the plasticizer and the total polymer component is 2.6:1 or higher.

2. The hot melt adhesive composition according to claim 1, wherein the hydrogenated linear styrene triblock copolymer of the first polymer component is selected from SEBS, SEPS, SEEPS, SBBS and blends thereof.

3. The hot melt adhesive composition according to claim 1, wherein the hydrogenated linear styrene triblock copolymer of the second polymer component is selected from SEBS, SEPS, SEEPS, SBBS and blends thereof.

4. The hot melt adhesive composition according to claim 1, wherein both the first polymer component and the second polymer component have a viscosity of 10% by weight of toluene solution at 30°C of 100 mPa·s or less.

5. The hot melt adhesive composition according to claim 1, wherein the first polymer component has a styrene content of 10 to 50%.

6. The hot melt adhesive composition according to claim 1, wherein the second polymer component has a styrene content of 5 to 50%.

7. The hot melt adhesive composition of claim 1, wherein the composition comprises at least one additional polymer component, said additional polymer component comprising an additional styrene block copolymer selected from SB, SI, SBS, SIS, SIBS.

8. The hot melt adhesive composition of claim 1, wherein the composition comprises a temperature-dependent coefficient of variation of peel strength of less than 0.

4.

9. The hot melt adhesive composition of claim 1, wherein the composition comprises a coefficient of variation of peel strength less than 0.4 depending on the amount added.

10. The hot melt adhesive composition of claim 1, wherein the composition is obtained by mixing the first polymer component, the second polymer component, the tackifying resin, and the plasticizer.

11. The hot melt adhesive composition of claim 1, wherein the composition does not contain butyl rubber.

12. The hot melt adhesive composition of claim 1, wherein the weight ratio between the plasticizer and the total polymer component is from 2.6:1 to 10:

1.

13. Use of the hot melt adhesive composition according to any one of claims 1 to 12 as an adhesive for bonding two substrates together, or as a coating on the surface of a substrate.

14. An article comprising at least one inner or outer surface coated with the hot melt adhesive composition according to any one of claims 1 to 12.

15. The article of claim 14, wherein the inner or outer surface is a nonwoven fabric.

16. The article of claim 14 or 15, wherein the article is selected from disposable diapers, disposable training pants, feminine hygiene products, absorbent pads, surgical masks, and surgical gowns.